Psychophysical research has shown that perceptual estimates of visual dimensions such as length, area, volume, and brightness are systematically related to actual stimulus values. However, the extent to which such fine-grained, continuous information is preserved in memory is only beginning to be investigated. The proposed research examines the degree to which information about perceptual magnitudes is preserved or trasformed in memory by comparing magnitude judgments made when stimuli are perceptually present with those made from memory. The work outlined below applies established psychophysical methods such as numerical magnitude estimation to the study of memory. Observers will make estimates of length, area, and other visual continua either from memory or while viewing the stimulus. Preliminary work with length and area suggests that, like perceptual estimates, memory estimates are related to actual stimulus magnitude by a power function. However, in the work completed to date, the exponents for the memory psychophysical functions have been approximately equal to the square of the perceptual exponents. A preliminary model that hypothesizes an additional transformation for memory judgments is proposed to account for these results. The proposed experiments test the generality of these empirical findings, the adequacy of the model, attempt to separate judgment and response effects in memory, and use reaction time methods to probe the process of memory-based comparisons.